[GRASSLIST:6884] Re: beginner's question

[Ian W. Macmillan]

Rahul,
Short answers follow, but hopefully they might point you in the right direction.


Quoting Rahul Chopra <rchopra at uchicago.edu>:
> Hello all,
>
> Am new to the mailing list and have a couple of novice like questions.
>
> 1. I have downloaded several Landsat ETM+ files which I wish to import into
> my GRASS location using r.in.gdal. Could someone provide some help with what
> the script might have to look like in order to import multiple tif files
> into this location?
SORRY NO HELP FOR YOU HERE.  I JUST USUALLY RUN R.IN.GDAL MULTIPLE TIMES


> 2. In order to apply radiometric corrections I ran grep BIAS dataset.met and
> get the message CORRECTION_METHOD_BIAS = "IC.  Does that mean that the
> radiometric corrections have already been applied? In the metadata file from
> GLCF's website it does say END_GROUP = CORRECTIONS_APPLIED
MOST GLCF FILES ARE ALREADY CORRECTED AND DON'T REALLY REQUIRE ANY POST
PROCESSING


> 3. When I  patch, say band 4 of  2 scenes I find a distinct difference in
> the intensity/brightness of the 2 scenes.  The sun elevation and sun azimuth
> are different in these 2 scenes? Is that the reason for difference in
> brightness? If so, how does one change the sun elevation and azimuth for one
> scene?
YOU CAN'T CHANGE THE SUN ELEVATION AND AZIMUTH OF THE SHOT, IT IS FIXED WHEN THE
IMAGE WAS TAKEN.  YOU CAN TRY TO FIND DIFFERENT LANDSAT IMAGES FROM DIFFERENT
TIMES THAT MIGHT MATCH, BUT IT RARELY WORKS OUT THAT YOU CAN FIND THAT.


> 4. One final question-- is there a program which accurately converts
> latitude longitude into UTM coordinates?

GRASS DOES THIS QUITE WELL (V.PROJ, R.PROJ) OR YOU CAN USE GDAL.

G'luck
-Ian